Recently, the Internet has become widespread, such that downloading contents such as audio or video data over the Internet for exploitation has come to be practiced frequently. In downloading the contents, billing processing is usually practiced at a time point of completion of the content downloading.
However, if, at a time point of completion of the content downloading, a power source button is intentionally operated in the OFF direction to turn off the power supply of a receiving terminal, only the content data is stored in the receiving terminal, without the billing processing, with the result that the content may be illicitly acquired free of charge.